The rapid development of the semiconductor industry and the increasing need for more and more unique semiconductor devices have resulted in the development of a variety of processes for producing such devices. A particularly interesting example is the group of processes involving photoelectrochemical etching of compound semiconductors. In such processes, light (or radiation of some kind) is needed to produce etching. Usually, the rate of etching is proportional to the intensity of radiation. This makes possible etching of various geometrical features on compound semiconductors including, for example, straight-walled holes, channels, etc. Some of these processes have been outlined in a variety of references including U.S. Pat. No. 4,404,072, issued to P. A. Kohl et al on Sept. 13, 1983; U.S. Pat. No. 4,389,291, issued to P. A. Kohl et al on June 21, 1983 and U.S. Pat. No. 4,369,099, issued to P. A. Kohl et al on Jan. 18, 1983.
Particularly rapid development has taken place in the last few years in one area of semiconductor technology namely the use of compound semiconductors in optical devices. Typical optical semiconductor devices are semiconductor lasers, light-emitting diodes, photodetectors, etc. Often, these devices require geometrical shaping to maximize efficiency, optical coupling, etc. A typical example is the fabrication of light-emitting diodes with lenses to collect and direct the radiation output of the light-emitting diode in a particular direction.
Typically, it is desired to produce a particular geometrical shape (e.g., a lens) with a surface of high optical quality so as to minimize scattering and undesirable reflections. In addition, rapid processing and batch processing are desirable to minimize cost and maximize manufacturing throughout. For example, in the production of LED devices, usually many devices are contained on a wafer and simultaneous processing would lead to rapid production and much reduced cost.